If you turn up the brightness really high in Calcium K, you can see faint prominences on the solar limb. These are quite ghostly and pale compared with hydrogen alpha imaging. Most people use a gradient map to colorise and enhance them then obscure the whited-out solar disc with a black fill. Here are 3 prominences in 2 images from 13th September 2014, the right hand image shows a nice loop prominence:
Click to enlarge image.